1. Field of the Invention
The invention relates to a laser irradiation apparatus, more specifically, to a medical laser irradiation apparatus for the treatment of tumors such as cancer or diseases such as benign prostatic hyperplasia by irradiating vital tissues with laser rays by means of inserting the apparatus into vital lumens such as blood vessels, urethras, and abdominal cavities, or puncturing internal organs with it leaving the long main body of the apparatus.
2. Description of the Related Art
A technique of treating lesions by means of laser irradiation apparatuses has been known, where the long and slender main body of a laser irradiation apparatus is inserted into a body cavity or a lumen formed by small discission and lesion tissues are irradiated with energy in order to diminish or clear the lesion tissues through alteration, sphacelation, coagulation, cauterization and evaporation.
The technique is generally to irradiate a lesion existing on the surface layer of a vital tissue or its vicinity directly. However, in order to apply this technique to a deep lesion, heating the lesion to a sufficient temperature, it is necessary to irradiate it with a laser ray of a relatively high power. As a result, there is a possibility damaging normal tissues adjacent to the lesion, such as the surface layer.
International Publication No. WO93/04727 disclosed a technique for coagulating and diminishing a tumor or a part of prostate by means of laser irradiation. The technique includes a method of using a cooling liquid led into a balloon in order to heat mainly the targeted internal tumor or the prostate minimizing the heating the surface of the urethra that is adjacent to the balloon. However, since the laser ray is irradiated from a fixed laser irradiator in this case, the technique has a drawback that it is necessary to use a low-power laser ray so as not to heat the surface of the urethra, thus resulting in a long irradiation time.
Unexamined Publication No. JP-A-6-154239 disclosed a laser irradiation apparatus to be inserted into the urethra for treating benign prostatic hyperplasia with laser rays. In this technique, multiple irradiation units placed at different positions radiate laser rays. The irradiated laser rays are converged on a target site in a deep legion to generate a sufficient heat for heating and diminishing the legion tissue. Consequently, the temperature in the vicinity of the target site becomes higher than other parts where the laser rays do not overlap. However, since the light paths of the laser rays are fixed, a certain region is created in the vicinity of the surface layer of the urethra where the laser rays do not overlap but the temperature is slightly higher. This phenomenon disadvantageously affects the protection of the surface layer of the urethra. Therefore, it is not completely satisfactory from the standpoint of treating only a deep lesion while preventing damages on the surface layer.
The object of the invention is to provide an apparatus that effectively irradiates a target site with laser rays, particularly a target site hidden deep inside a vital tissue, while easily and securely preventing damages to normal tissues, particularly, normal surface tissues that are in contact with the laser irradiation apparatus.
The specific object of the invention is to provide a laser irradiation apparatus comprising: a long and slender main body; a light conducting member, which is placed inside said main body and which is equipped with a proximal end through which the laser rays are introduced and an emitting part from which the laser rays are irradiated sideways or diagonally, wherein said emitting part of said light conducting member can move reciprocally in the axial direction within a certain range; and a reflecting member, which is affixed to the inside of said main body to reflect the laser rays irradiated from said light conducting member, wherein said reflecting member having a reflecting surface that changes its reflecting angle as said emitting part moves along its reciprocating movement range.
The laser irradiation apparatus of the present invention makes it possible to converge the laser rays emitted from the continuously moving emitting part on the target site or its vicinity. This enables areas other than the target site to be maintained at relatively low temperatures. Thus, the damages to areas other than the target site will be prevented or kept minimum, so that it can provided a high treatment effect. It is particularly effective in a case where the target site is hidden deep inside the vital tissue as the damages to the surface layer can be kept minimum.